refactor(i18n): replace language-settings with locale-switcher

- Replace react-world-flags with next/image for better optimization
- Simplify locale handling logic and remove unused getUserLocale
- Rename component to be more descriptive (language-settings -> locale-switcher)
- Update all references to use the new component
- Add proper SVG flag assets for supported locales
- Remove react-world-flags dependency from package.json

public/flags/cn.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 30 20"><defs><path id="a" d="M0-1L.588.809-.952-.309H.952L-.588.809z" fill="#FF0"/></defs><path fill="#EE1C25" d="M0 0h30v20H0z"/><use xlink:href="#a" transform="matrix(3 0 0 3 5 5)"/><use xlink:href="#a" transform="rotate(23.036 .093 25.536)"/><use xlink:href="#a" transform="rotate(45.87 1.273 16.18)"/><use xlink:href="#a" transform="rotate(69.945 .996 12.078)"/><use xlink:href="#a" transform="rotate(20.66 -19.689 31.932)"/></svg>

public/flags/us.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 7410 3900"><path fill="#b22234" d="M0 0h7410v3900H0z"/><path d="M0 450h7410m0 600H0m0 600h7410m0 600H0m0 600h7410m0 600H0" stroke="#fff" stroke-width="300"/><path fill="#3c3b6e" d="M0 0h2964v2100H0z"/><g fill="#fff"><g id="d"><g id="c"><g id="e"><g id="b"><path id="a" d="M247 90l70.534 217.082-184.66-134.164h228.253L176.466 307.082z"/><use xlink:href="#a" y="420"/><use xlink:href="#a" y="840"/><use xlink:href="#a" y="1260"/></g><use xlink:href="#a" y="1680"/></g><use xlink:href="#b" x="247" y="210"/></g><use xlink:href="#c" x="494"/></g><use xlink:href="#d" x="988"/><use xlink:href="#c" x="1976"/><use xlink:href="#e" x="2470"/></g></svg>